During the consultation, we often encounter pregnant women with hepatitis B who ask if they can undergo amniocentesis for prenatal diagnosis. Not everyone who is pregnant needs to have an amniocentesis. The main purpose of amniocentesis is for patients who need prenatal diagnosis, including those who are at high risk for Down’s syndrome, such as those who are older than 35 years old. If the test index is more than 1/250, it is also a high risk and prenatal diagnosis is recommended. Then there is the prenatal diagnosis that is also recommended for women who have previously had a child with Down’s syndrome or malformation to get pregnant again. If the fetus is found to have a serious heart malformation, intestinal obstruction or urinary tract fluid through ultrasound during pregnancy, prenatal diagnosis is needed to rule out chromosomal abnormalities, and if these malformations are not combined with chromosomal abnormalities, there is a time for surgery to correct the child after birth. However, if the chromosomal abnormalities are combined with Down’s syndrome, even if the surgery is done, the child’s intelligence and other problems will be a financial burden to the society and the family. There are also some groups of people, such as those with familial hereditary disease thalassemia, where both husband and wife are carriers of the same type, who need to determine if the child is severely thalassemia and need to undergo amniocentesis. There are also cases where the mother is Rh-negative and the child is suspected to have Rh-inappropriate hemolysis, which requires amniocentesis. If intrauterine infection is suspected, such as small fetal growth, atypical malformations, or edema-like changes in the fetus, it is necessary to find out if the fetus has a specific viral infection, and a prenatal diagnosis such as TORCH test is required. If the pregnant woman is only a hepatitis B carrier: the test results are: only positive hepatitis B surface antigen, normal liver function, HBV-DNA copy less than 3 times 10, the pregnant woman is 35 years old or older, or less than 35 years old, but the prenatal screening results are high-risk, or the ultrasound examination suggests that the fetus may be abnormal, or has previously given birth to a malformed child or a child with serious genetic disease. Or if one of the spouses has a chromosomal abnormality, it is possible and very necessary to perform prenatal diagnosis by amniocentesis. If the patient is a hepatitis B patient, the results of the five quantitative hepatitis B tests, especially the e antigen test, the HBV-DNA quantification and the liver function tests are required. The pros and cons of amniocentesis should be weighed against the risk of having a malformed or mentally retarded child. In practice, the likelihood of a fetus being infected with hepatitis B as a result of amniocentesis is very small. If a pregnant woman has a high hepatitis B viral load, it is possible that the embryo may have been infected with hepatitis B before the amniocentesis. Amniocentesis is performed by a doctor in a proper hospital according to strict aseptic protocols. It is necessary to be tested for the 4 infectious diseases (Hepatitis B, Hepatitis C, Syphilis and HIV) before the amniocentesis.